Method for making cutter blades



Jan. 24, 1939. F. P. MILLER 2,

IETHOD FOR MAKING CUTTER BLADES Filed Aug. 20, 1936 Awg u I FRANK P. IT/LLER aw Jan- 24, 193a .umreo S ATES Phil-INT This invention mamas! terminus 881M "blades it: an I m I "the present appiicationbeing a input r oi my'applicationfleriai No.30), iiled'itovemher 1I,'193. 5;. a Y Theme or serratedbl'ades-in cutter-headset vu-ioustypes is practice throughout the metalcutting industries. However, the iorming oi presents certain seriourdii flcultiesin manuiactureandgivesrisetjopmblenn whichitis invention tosolve.

'Inma'kingserratedbladestromtooisteelain- .cliuiing'thevariousgradesothighspeedsteel.

itiscustomaryt'oioruithesel'rationswith'ahobv when the blades are in an annnledcondition. after which it is. of necessary to sub- Ject the bladeato treatment at high toproduce the required hard QO-ness. This heat treatment results in a certain .quirea grindlng wheel with adeilnitely'thinand tapering V-shaped grinding portion; inherently fragile and necessitating slow careful feeding into the work. with frequent interruptions in grinding 35 for the purpose of redressing the wheel. Furthermore, when the V-shaped serrations are so close togethergit is necessary to grind one at a time, since it is commercially impracticable to maintain an accurate contour on the grinding 40 surface of the wheel consisting of closely juxtaposed sharp \L-grooves and ridges, which in many casesaresoiixieincross-sectionasto-resultin thirty-two ridges and thirty-two grooves in one inch, eachgroove andeachridge havingasharp 45 point Qiat must be maintained at all times.

It is obvious that in making serrated blades irom non-machineabie metal such as Btellite, tungsten carbide, etc., there isno choice as to method and the serrations must be formed by a 50 grinding wheeL-regardless oi the cost of doing so.

My parent application above; referred to describes a new form of serrated blade which reduces bypne-hali the number!!! serrations to-be formed and also makes possible a new, simple 55 and inexpensive method of grinding'the serrais the subject of this ap- Cutter blades produced by this method the serrations are per-' iec'tly are. free from, distor- -tion andfandiit perfectly the serrations .5

'l'hisisessentialifthebladesareto -withstandzthepressures oi heavycuts without yielding; a blade um y'leids ever so slightly will soon its cutting edge and will not produce work. aiurther result of this invention 10 infthe fact that serrated blades can be by thismethod at almost as low a cost,

"Dllm bladeswithout serrations. The total result is a superior product at a greatly reduced cost of'manuiacture; v

with an appreciation of the foregoing, another object oithe invention is the method of grinding the serrations with a grinding wheel havinga flat suriaceor land'equal in width to not less base of one serration, the groove thus formed between blade serrations being suiiicient to. embrace two or more serrations in the cutter A further object oi the invention is the provision of a grinding wheel having the grinding surface contoured to produce the blade serrations as described which, by virtue of the obtuse sunangiesjbetween the sides of the wheel and the land, is durable and long-lived, requiring I drening only-at protracted intervals, permitting higher speed in operation, with the; result of accelerated output.

Otherobiects oi the invention will appear as the followingdescription of a preferred and practical embodiment thereof proceeds. .j

--,In.the'drawing forming a part of: this application and in which like numerals are-employed-to designate like parts throughout the same, 4

Figures 1 and 2 contrast the new with the old, Figure 1 being a fragmentary section of a blade embodying the principles oi the present invention, showing also, in fragmentary elevation, the grinding wheel by which this formof blade is produced,

Figure 2 is a. similar view of a blade and grinding wheel of known construction,

mure 3 is a view similar to Figures 1 and 2 showing a grinding wheel capable of making a plurality of serrations at one time,

Figure 4 is a view partly in section and partly in elevation showing a cutter head with inserted blade made'according to the present invention,

Figure 5 is a view in elevation showing a. grindf ing wlieel of considerable width in grinding contact with a blade held in the jaws of a vise,

- Figure .6 is a fragmentary plan view of acutter the same results.as though both serrated surfaces were alike. e

Referring now in detail to the several figures, the numeral I represents a blade of "Stellite or the like or hardened tool steel having a pluraliity of close'serrations 2. The grinding wheel! for making these serrations is shown to have a' v=shaped periphery with an acute apex 4. This is a shape that breaks down readily under the stress of grinding, with the result that it is frequently necessary to interrupt production for the purpose of redressing the grinding wheel. Further, the shape of the grinding portion of the wheel 3 has a definitely limiting effect on the allowed speeds and feeds so that rapid production is further interfered with.

In Figure 1, which illustrates the present invention, the serrations 5 are spaced apart double the width of a serration so that the serrations 5 of the blade I5 fit in'every other groove 6 in the blade receiving recess in the cutter head. See Figure 4.-

In'providing for generousspaces between the serrations 5 of the blade, I am able to use a grinding wheel I having a broad land 8, as distinguished fromthe thin and tapering grinding periphery of the wheel 8 in Figure 2, the land 8 being flanke'd on both sides by obtuse shoulders or supporting angles 9. It is obvious that the wide land 8 will, hold its shape much longer than the sharp apex 4 of the'wheel shown in Figure 2 and can be fed into the work more rapidly. This overcomes the need of frequent blade as compared with the usualform of ser rated blade illustrated in Figure 2.

Fig. 3 represents a still further advance in the method of producing serrated blades, and is merely an extension of the idea shown in Fig.

- 1. The grinding w eel l2 shown in Fig.- 3. is

formed with a plur lity of grooves ill for pro ducing several of the serrations 5 at one time. This wheel may be integral or comprise a group of thin g ding wheels clamped together. It is obvious to anyone skilled in' the grinding art that there is no serious diiiiculty in making a V-shaped groove such as the grooves IQ in Fig.

In the case of a groove, the grinding pressure comes mostly on the sides of the groove and the .point at the bottom of the groove is well supported at both sides; In the case of a V-point, as shown on the wheel in Fig. 2, the first point of contact is the acute point itself, and this is not supported on either side and thus quickly breaks down.

As shown in Figure 5, the grinding wheel I2 is mounted on a driven shaft I3 of any good design of surface grinding machine having a reciprocating table to carry the blades back and forth under the wheel and, of course, in engagement therewith for forming the serrations therein. The blade i5 may be held securely in place between the jaws ll of a vise or other holding means associated with the table.

Figures 4, 6 and .7 show clearly how reducing the number of serrations in the blade does not interfere at all with the fineness of adjustment d rations 'on a blade holder, comprising bringing one side of the blade into contact with a rotating abrasive wheel having upon its periphery a blunt elevation, said elevation having inclined sides to shape the inclined sides of the blade serrations, and said elevation being of a cross-sectional area equal to the combined cross-sectional area of a plurality of the serrations to be formed on the cutter blade, maintaining the blade in contact with the wheel, and effecting relative movement between the blade and wheel transversely of the wheel aids to form in the blade the inclined side faces of adjacent serrations and an intervening groove of sufficient width to receive a plurality of holder serrations.

2. The method of forming parallel adjustment serrations in a hard or hardened cutter blade for cooperation with a greater number of serrations on a blade holder, comprising bringing one side of the'blade into contact with a rotating abrasive wheel having upon its periphery a plurality. of alternateannular elevations and grooves, each elevation being of a crosssectional area equal to the combined cross-sectional area of a plurality of said grooves, maintaining the blade in contact with the wheel, and at the same time effecting relative movement between the blade and wheel transversely of the wheel axis to simultaneously form in the blade a plurality of parallel serrations spaced apart suiiiciently to'receive between each pair thereof a plurality of holder serrations.

.FRANKP.I\HLLER. 

